Epilepsy is a chronic brain disorder characterized by episodic seizures caused by excessive brain cell firing. The excessive brain cell firing is a result of various etiologic factors, and, accordingly, progression and prognosis of the seizure can vary greatly depending on the type of epilepsy. Therefore, accurate diagnosis and appropriate procedure are required for treating epilepsy.
An epilepsy model animal has been used as means for developing and progressing diagnostic and treatment methods of epilepsy. As the epilepsy model animal, drug-induced epileptic animals produced by administration of kainic acid and kindling (method of repeating brain stimulation with electricity under a threshold value)-induced epileptic animals have heretofore been used.
However, the conventional model animals are not more than animals in which convulsive seizure is forcibly induced and could not be used as true models for human epilepsy although they could be used as model animals of “convulsive seizure”.
Meanwhile, thanks to recent progress in molecular biological studies, gene abnormality is being identified in several types of epilepsy. The inventors of this invention have found that there is a relationship between human chromosomal dominant nocturnal frontal lobe epilepsy and mutation of a neuron nicotinic acetylcholine receptor α4 subunit (CHRNA4) gene (Non-Patent Document 1) and that the mutation of CHRNA4 is specifically a substitution of Ser at position 284 by Leu (Non-Patent Document 2).    Non-Patent Document 1: Hirose, S. et al., Neurology 53: 1749-1753, 1999.    Non-Patent Document 2: Matsushima, N. et al., Epilepsy Res. 48: 181-186, 2002.